INTRODUCTION. By Dr. A. Skitz. 7 



■200 known forms inluilMt the western continent, and only about a dozen of these occur in temperate 

 Xorth America. 



It might appear singular that a family whose females are each and all immovable should have such 

 an enormous range as the Psj'chids, which are represented in the remotest islands, such as New Zealand, 

 Teneriffe. etc., and often by characteristic species. But it must not be forgotten that their larvae are 

 extremely active and endowed with great powers of resistance, and many, if not all the species are 

 parthenogenetic, i. e. capable of propagating without previous copulation. Nothing would be more erroneous 

 than to infer the existence of a submerged continent from the occurrence of the Psychids on both coasts 

 of the Atlantic. Their transplantation from America to the Old World and vice versa could very easily be 

 effected by drift-wood. I have fished out from the Plata River floating boughs on which a number of cases 

 of Oifceticiis plafeiisis were spun up, some containing sound larvae, others living pupae. It appeal's that the 

 larva is capable of making its case watertight. I found large Psychid cases on the coast of North-Shore 

 in the harbour of Sydney, Australia, which were spun up on the rocks, and over which every wave washed 

 at flood-tide; they contained uninjured larvae. Thus their transplantation by means of drift-wood is not at 

 all improbable ; indeed they are not even threatened by many special dangers for their long and troublesome 

 voyage. Psychid larvae can fast for a verj- long time, and when this is no longer possible to them, any 

 food is accepted. The larvae of Amicta febrett<t, which I took in numbers in North Africa from a dry 

 desert-plant, were fed up to the pupal stage in Europe on pear-peel; and inasmuch as a single female 

 Psj-chid is sufficient to increase the range of a species, the greater wonder is that no species of this 

 family is cosmopohtan . indeed that there is none which is possessed bj^ America in common with the 

 Palaearctic fauna. 



The Lasiocampids as a whole are not yet sufficiently well known to allow of our forming a 

 definite judgment as to their distribution. Without doubt America has over one-third of the 800 — 1000 

 existing forms. With the ver\' large number of species which are already known from South America, it 

 must be assumed that a more thorough exploration of the interior of Brazil will bring to light many more. 

 As at present constituted, the group is not even homogeneous, so that many alterations are to be expected 

 when the Neotropical forms, in particular, are fully worked out. As the family is now constituted, America 

 possesses numerous exceptionally interesting forms. The larvae of the genus Megalo'pyge, remarkable for 

 their peculiar tufts of hairs, are dreaded in America on account of the inflammation which these hairs 

 cause. In one lady who came under my treatment they had produced swellings on the arm and breast, 

 with several days' fever, so that their effects even exceed in intensity those of the hairs of Thaumatopoea. 

 Sometimes there is an unusually pronounced sexual dimorphism in this family, as in Heliconisa pagenstecJieri, 

 whose female was long known as Dirphia costoi-K. In the New World , as in the Old , some of the 

 Lasiocampids are of economic importance. 



The Saturnids, of which there are somewhat over 400 species in all, are almost equally divided 

 between the New World and the Old. In this magnificent group the relative richness of America is shown 

 by its attaining, in the number of its Saturnids, to a total equalling those of the great continents of Asia 

 and Africa combined. Against six for the whole of Europe, some 40 forms inhabit temperate North America. 

 The Ceratocampids, too, which are related to the Saturnids, and of which there are about 50 forms, 

 belong to America alone; whilst the Brahmaeids of the east possess hardly more than a dozen forms. On 

 the other hand America is somewhat behind the Old World in respect of the true Bombycids. 



The American Sphingids , in comparison with those of the Old World , show a proportion of 3 : 5, 

 370 out of about 1000 knowm forms occurring in the New World. The exhaustive work of Rothschild 

 and JoRDAK has thrown a ver\' full light on the distribution of this family. America is particularly rich in 

 gigantic hawk-moths, such as Facliylia, Cocytius, Pholus, Pseudosphinx , etc. One would expect, from the 

 extensive powers of flight of most Sphingids, that quite a number of representatives of this group would 

 be common to both hemispheres, which, however, is not the case; only quite a few species, such as Celerio 

 lineato and yallii, appear in both without any very material differences. 



In the Notodontids we have another heterogeneous group, in the composition of which alterations 

 will certairdy be made — at least by its sphtting up into several groups — when it is worked out morpho- 

 logically with a regard for the finer anatomical details. *) It is therefore of little value to fix the number 

 which belong to the Western Hemisphere, out of the 600 odd species at present placed in the Notodontids. 

 They form by far the greater part; the genera liosema, with grass-green forewings, Nystalea , with its 

 noctuid habits, the Xorth American Dafxina, Heterocampa, etc., are rich in species which play an important 

 part in the western continent on account of their richness in individuals. 



In the Noctuids, conditions are much the same as in the Old World, especially as described in 

 deahng with the Palaearctic Noctuids (vol. Ill, p. 11): in the south more diurnal species, in the north duller 

 coloured genera {Mamestra, Acronida, Ayrotis, Haclena, etc.) which sleep by day; but in the north, in 

 addition, a wide distribution of the Catocalids, lightly .sleeping night-fliers which are specially adapted for 



*) As Packard has done for the North American species. 



